Effect of ethephon and 6-benzylaminopurine on chlorophyll degrading enzymes and peroxidase-linked chlorophyll bleaching during post-harvest senescence of broccoli (Brassica oleracea L.) at 20º C

COSTA, M. LORENZA; CIVELLO, PEDRO M.; CHAVES, ALICIA; MARTÍNEZ, GUSTAVO

POSTHARVEST BIOLOGY AND TECHNOLOGY

Elsevier - Science

Lugar: Washington, Estados Unidos; Año: 2005 vol. 35 p. 115 - 222

0925-5214

Abstract Effects of ethephon and 6-benzylaminopurine (BAP) treatments on enzyme degrading enzymes and a peroxidase-linked chlorophyll bleaching were investigated in broccoli (Brassica oleracea L.) florets. The florets were dipped in solutions containing either BAP or ethephon and then incubated in darkness at 20 ◦C. The hue angle values and chlorophyll contents of ethephontreated florets declined the most of the five-day experiment. In contrast, hue angle and chlorophyll content declined the least in BAP-treated florets. Pheophytin levels increased the most in ethephon-treated florets and the least in BAP-treated florets. Chlorophyllase, Mg-dechelatase, and peroxidase-linked chlorophyll bleaching increased over the five days in control (untreated) florets. Ethephon treatment enhanced chlorophyllase, Mg-dechelatase, and peroxidase-linked chlorophyll bleaching levels as compared with control. BAP treatment reduced chlorophyllase, Mg-dechelatase, and peroxidase-linked chlorophyll bleaching levels. It was concluded that the activities of chlorophyllase, Mg-dechelatase, and peroxidase-linked chlorophyll bleaching could be regulated by external application of either ethylene (applied as ethephon) or a cytokinin (applied as BAP). In the case of ethephon treatment, accelerated rates of chlorophyll degradation were found and in the case of BAP-treatment, reduced rates of chlorophyll degradation were found. Keywords: Broccoli; Chlorophyll degradation; Ethephon; BAP